This invention relates to a vehicle shock absorber, and more particularly, the invention relates to an apparatus for removing ice and debris from a shock absorber rod.
Vehicle shock absorbers such as those used in snowmobile and other cold weather applications may have problems of rod icing inhibiting proper operation of the shock absorber. Snow and ice become compacted around the shock absorber rod preventing the rod from moving in and out of the cylinder. Prior art devices have proposed a scraper to scrap the ice and other debris from the rod. However, these prior art devices utilize separate support rings and other components to support the scraper, which increases the dead length of the shock absorber and adds cost to the assembly.
Thick metal scrapers have been press fit to the rod. A large force must be applied to the rod to overcome the press fir of the scraper onto the rod, which is undesirable. The press fit between the scraper axis rod is along the entire inner surface of the scraper, which results in a rather large surface area requiring a large load to overcome the press fit. Furthermore, cylinder heads utilizing the scrapers have been rather difficult to assembly because they require numerous components to be retained in the cylinder head at both ends of the cylinder head. Specifically, many support or snap ring must be used at the ends of the cylinder at assembly. Therefore, what is needed is an improved scraper for a shock absorber.
The present invention provides a vehicle shock absorber including a piston rod. A cylinder head having a bore defining an axis supports the rod within the bore. A wiper, which preferably a hard plastic, is disposed within the cylinder head. The wiper has in inner surface that is in an interference fit with the rod. The wiper has spaced apart upper and lower contacts that are press fit to the rod. The inner surface tapers away from the upper and lower contacts to a generally central portion forming a cavity. The inner surface is spaced from the rod in the area of the cavity. In this manner, the interference between the wiper and rod is minimized forming only line contacts about the rod. The outer circumference of the wiper is preferably spaced from an annular pocket in the cylinder head receiving the wiper to permit the wiper to move laterally as its scraps debris from the rod. The cylinder head components are installed from the inner side of the cylinder head and a plate is press fit into the end of the cylinder head.
Accordingly, the above invention provides an improved scraper for a shock absorber.